Adaptation of exercise-induced stress in well-trained healthy young men

Strenuous exercise induces different stress-related physiological changes, potentially including changes in intestinal barrier function. In the Protégé Study (ISRCTN14236739; www.isrctn.com) we determined the test-retest repeatability in responses to exercise in well-trained individuals. Eleven well-trained males (27 ± 4 years old) completed an exercise protocol that consisted of intensive cycling intervals, followed by an overnight fast and an additional 90 min cycling phase at 50% Wmax the next morning. The day before (rest), and immediately after the exercise protocol (exercise) a lactulose/rhamnose solution was ingested. Markers of energy metabolism, lactulose/rhamnose ratio, several cytokines and potential stress-related markers were measured at rest and during exercise. In addition, untargeted urine metabolite profiles were obtained. The complete procedure (Test) was repeated one week later (Retest) to assess repeatability. Metabolic effect parameters with regard to energy metabolism and urine metabolomics were similar for both the Test and Retest period, underlining comparable exercise load. Following exercise, intestinal permeability (one hour plasma lactulose/rhamnose ratio), serum interleukin-6, interleukin-10, fibroblast growth factor-21, and muscle creatine kinase levels were only significantly increased compared to rest during the first test and not when the test was repeated. Responses to strenuous exercise in well-trained young men, as indicated by intestinal markers and myokines, show adaptation in Test-Retest outcome. This might be due to a carry-over effect of the defense mechanisms triggered during the Test. This finding has implications for the design of studies aimed at evaluating physiological responses to exercise

Adaptation of exercise-induced stress in well-trained healthy young men

Strenuous exercise induces different stress-related physiological changes, potentially including changes in intestinal barrier function. In the Protégé Study (ISRCTN14236739; www.isrctn.com) we determined the test-retest repeatability in responses to exercise in well-trained individuals. Eleven well-trained males (27 ± 4 years old) completed an exercise protocol that consisted of intensive cycling intervals, followed by an overnight fast and an additional 90 min cycling phase at 50% Wmax the next morning. The day before (rest), and immediately after the exercise protocol (exercise) a lactulose/rhamnose solution was ingested. Markers of energy metabolism, lactulose/rhamnose ratio, several cytokines and potential stress-related markers were measured at rest and during exercise. In addition, untargeted urine metabolite profiles were obtained. The complete procedure (Test) was repeated one week later (Retest) to assess repeatability. Metabolic effect parameters with regard to energy metabolism and urine metabolomics were similar for both the Test and Retest period, underlining comparable exercise load. Following exercise, intestinal permeability (one hour plasma lactulose/rhamnose ratio), serum interleukin-6, interleukin-10, fibroblast growth factor-21, and muscle creatine kinase levels were only significantly increased compared to rest during the first test and not when the test was repeated. Responses to strenuous exercise in well-trained young men, as indicated by intestinal markers and myokines, show adaptation in Test-Retest outcome. This might be due to a carry-over effect of the defense mechanisms triggered during the Test. This finding has implications for the design of studies aimed at evaluating physiological responses to exercise

Identification of a new cluster of T-cell receptor delta recombining elements

Within the human T-cell receptor δ (TCRD) gene we have identified a new cluster of seven δ recombining elements (δRec2.1–2.7), located 2·6–5·2 kilobases downstream of the Vδ2 gene segment. The δRec2 elements are isolated recombining signal sequences (RSS), which were shown to rearrange with the Dδ3 and Jδ1 segments of the TCRD gene as well as with the ψJα of the TCRA gene. Rearrangements involving the δRec2 elements were found in all peripheral blood (PB) samples from 10 healthy individuals, although their frequency was about 100-fold lower than that of classical δRec rearrangements. The total frequency of δRec2 rearrangements was lower in PB T lymphocytes, as compared with thymocytes, suggesting that they are deleted during T-cell development. The decrease of the frequency of the δRec2-Dδ3 rearrangements was most prominent: 11 times lower in PB T lymphocytes than in thymocytes. Since the δRec2-Jδ1 rearrangements contained the Dδ3 segment in the junctional region, we assume that they are derived from the δRec2-Dδ3 rearrangements. In contrast, the majority of δRec2-ψJα rearrangements did not contain the Dδ3 segment, indicating that they are single step rearrangements. The δRec2-Jδ1 and δRec2-ψJα rearrangements seem to be T-lineage specific, but the δRec2-Dδ3 rearrangements were also found at very low frequencies in B lymphocytes and natural killer cells. Our results suggest that δRec2 rearrangements are transient steps in the recombinatorial process of the TCRAD locus and are probably deleted by subsequent Vα-Jα rearrangements. We hypothesize, that in a similar manner to the classical δRec rearrangements, the δRec2 rearrangements might also contribute to T-cell differentiation towards the TCR-αβ lineage